Centrifugal casting method



Oct. 20, 1931.

w. H. MILLSPAUGH 1,828,335

CENTRIFUGAL CASTING METHOD Filed April 26 1929 .2 Sheets-Sheet l M INVENTOR I/M/mm AIM/spay} ATTORNEYS K Oct. 20, 1931. W.'H. MILLSPAUGH CENTRIFUGAL CASTING METHOD 2 Sheets-Sheet 2 Filed April 26. 1929 AZ/WW/Y ATTORNEYS Patented Oct. 20, 1931 UNI ED STATES PA ENrorFmE t i i WILLIAM H. MILLSPAUGH, OE SAN'DUSKY, OHIO, ASSIGNOR TO THE PAPER 8 TEXTILE MACHINERY COMPANY, OF SANDUSKY, OHIO, A. CORIEORATION.OF ")HIO onnrmrnenx. casrme mnrnon Application filed April 26,

This invention relates to improvements in centrifugal casting and more particularly to a method of controllino the rate of diss pating the heat of the molten metal poured 1nto a rotatable mold. The invention relates specifically to the method of cooling the molten metal at different .desired ratesby provlding molds of difierent heat dissi atlng properties as by the use of molds 0 difi'erent wall 10 thickness for castings of difl'erent thickne'ss or of diiferent metals or materials.

It is well known that the problems connected with the cooling of centrifugal castings such as tubular or substantiall cylindrical articles, are much more comp ex than the problems of cooling floor castings. The heat of the metal poured into rotatable molds 1s dissipated both inwardly and outwardly and with .certain metals it is essential to control the rate of the outward heat dissipation for if it is too rapid the metal will crack and if it' it is too slow, the desired character of metal in the casting will not be produced. I have discovered that by the simple expedient of proportioning the thickness of the wall of the mold to the thickness of the casting made therein, the rate of cooling can be controlled, and that by using thicker mold walls for thicker castings and vice versa, the former difliculties are overcome.

The molds used in the rotors of centrifugal casting machines are removable and inter changeable so that as soon as a casting has set, it, with its mold may be removed from the rotor and another mold of the same or different type inserted. The casting iscooled within its mold but not necessarily within the rotor of a casting machine. According to this invention castings of manydifi'erent, diameters and Wall thicknesses may be made in one rotor. I am aware of the fact that it has been suggested in general terms, that castings of different sizes may be produced in one machine, but this has not been accomplished practically because it has not been known that merely changing the internal diameter of the mold to get castings of dififerent external diameters, is not enough to get good results. But I have found that for a casting .60- of a given thickness, a certain mold wall 1929. Serial in. 358,231. l

thickness is required, regardless of the outside diameter of the casting, also that for castings of different thickness but of the same outside diameter, different mold vvwall thicknesses are'needed.

In order to more clearly disclose my invention,'drawings are submitted to illustrate diav grammatically various ways of practicing the novel method. All of the drawings are transverse sections taken through a rotor, a mold Figs. 1, 2 and 3 show three castings A, B

and C of the same outside diameter but of different thicknesses. The mold 20A for the thinnest casting A has a thinner wall than the mold 2013 for the thicker casting B, and the mold 200 for the thickest casting C, has the thickest wall. Each of these molds is provided with spacing ribs 21A, 21Band 21C or equivalent elements which serve the twofold function of making each of the molds fit the same rotor, and of providing an insulating air space between the outside of the mold and the inside of the rotor.

I Fig. 4 illustrates a large diameter thin casting D on a thin walled mold 20D, spaced from rotor 10 by ribs 21]). It is obvious that a great variety of other sizes of castings of different thicknesses may bemade in the same rotor according to this principle.

The method may be practiced also with refractory molds as shown in Figs. 5-7. In these figures each coinprisea metallic shell which I call a.core-case and a liner of sand or other refractory material.

In Figs. 5 and 6 the same core-case is shown. It comprises a body 30 with spacing ribs 31,

,or equivalent elements, which are similar to and serve the same purpose as the ribs in the I previous figures, and perforations 32 for the escape of gases from the refractory material into the spaces between the outside of the core-case and the inside of the rotor. A. in walled casting of large diameter i h wn at E in Fig. 5. This is cast on a r fra tory liner 33, the thickness of which together with the thickness of the core-case is comparatlvely thin. That is the thickness of this compound mold is proportioned to give the desired rate of heat radiation and dissipation for such a casting as that shown at E.

The casting 1* shown in Fig. 6 1s of smaller diameter and! has a thicker wall than that shown in I ig. 5. In this case a thicker refractory liner 33A is used. It has been assumefd heretofore that a casting of the diamt frf casting F and no thicker than casing E could be made in the mold shown in Fig. e. and this assumption has been the reason for the non-development of making castings of different diameters in the same machine, for with some metals and under usual conditions this cannot be done. However, Figs. 5 and 6 show that castings of different diameters may be made in the same core-case.

ten metal poured into rotatable molds and controlling the rate of said outward heat dissipation, by'proportioning the thickness of the mold walls in accordance with the thickness and material of the castings made therein, to establish the heat conducting characteristics of the molds.

4. The herein described method of making hollow centrifugal castings of uniform wall thicknesses which comprises providing for a uniform outward heat dissipation from molten metal poured into rotatable molds and controlling the rate of said outward heat dissipation, by providing molds having walls of homogeneous heat conductivity and proportioning the thickness of said walls in accordance with the thickness and material of the castings made therein, to establish the heat conducting characteristics of the molds.

In witness whereof, I have hereunto set my hand this 3rd day of A ril, 1929.

WILLIAM H. M LLSPAUGH.

When it is desired to make a casting of the same diameter as casting F and of the thickness of casting E, a different core-case must be used as shown at 30A in Fig. 7 G designates such a. casting and 33B its refractory liner. The combined thickness of the corecase 30A and its liner 3313 in F ig. 7 is slightly less than the thickness of the compound mold 30, 33 of Fig. 5 because there is less metal in casting G than there is in casting E. This showing is based upon the assumption that castings G and E are of the same metal and are poured at the same temperature. Of

course variations in the mold wall thicknesses are made to meet the requirements of the metals and pouring temperatures used.

\Vhat I claim is:

1. The herein described method of making hollow centrifugal castings which comprises providing for outward heat dissipation from molten metal poured into rotatable molds and controlling the rate of said outward heat dissipation, by proportioning the dimensions of the mold walls in accordance with the character of the castings made therein, to establish the heat conducting characteristics of the molds.

2. The herein described method of making hollow centrifugal castings of uniform wall thicknesses which comprises providing for a uniform outward heat dissipation from molten metal poured into rotatable molds and controlling the rate of said outward heat dissipation, by proportioning the thickness of the mold walls in accordance with the character of the castings made therein, to establish the heat conducting characteristics of the molds.

3. The herein described method of making hollow centrifugal castings of uniform wall thicknesses which comprises'providing for a uniform outward heat dissipation from mol- 

